


Just Some Stress Relief

by Bitterhawkshaw



Category: The Last Hours Series - Cassandra Clare, The Shadowhunter Chronicles - Cassandra Clare
Genre: Blow Jobs, M/M, One-Sided Attraction, Oral Sex
Language: English
Status: Completed
Published: 2021-01-22
Updated: 2021-01-22
Packaged: 2021-03-13 23:56:06
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,572
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28911954
Author URL: https://archiveofourown.org/users/Bitterhawkshaw/pseuds/Bitterhawkshaw
Summary: Thomas is big and reckless, and he needs something to calm his nerves
Relationships: Alastair Carstairs/Thomas Lightwood
Kudos: 43





	Just Some Stress Relief

**Author's Note:**

> The working title for this fic was "how does it feel to get cucked in your own home Charles Fairchild"
> 
> Was originally started in march after reading Chain of Gold, just got around to actually finishing it!

Alastair and Thomas clambered down the steps into the laboratory. Thomas put down the small box that held the malos root on the table. Now that he was actually in front of the chemistry set, he wasn't sure if James's faith that he could do what Christopher does was put into the correct place. He gulped

"What do you need me to do?" Alastair said beside him. His voice was strained and a little rushed, but Thomas already felt calmer by Alastair's side. If Thomas didn't know what he was doing, Alastair knew even less. Alastair was counting on him, everyone was counting on him.

Thomas told Alastair how to set up the chemistry set, while Thomas tried to prep the malos root. Alastair followed Thomas's every order without even the smallest smug or snapped remark.

Soon enough, the root had been crushed, the bunsen burners turned on, and all they had to do was wait. And the whole time Thomas's hands were shaking. He'd definitely almost dropped a beaker or two at points. Thomas laughed off each one, but Alastair seemed to grow more annoyed and frustrated with Thomas, but he still didn't say anything. Just followed orders.

Once the antidote was in the final beaker, all they could do was wait until there was enough to bring to the Silent City to (Thomas hoped) cure those getting treatment there. As they waited Alastair finally spoke.

"For such a large man I didn't expect you to be so skittish."

"I'm just nervous," Thomas responded. "I'm worried if I mess up it will just kill the sick  _ faster _ . I don't want Christopher and Ariadne to end up like Barbara.

At the sound of the Inquisitor's daughter's name Alastair flinched ever so slightly. It was barely noticeable, but Thomas caught a glimpse of hurt behind Alastair’s black eyes. .

If Alastair was...engaged...with Charles Fairchild, he must've been the first to know about Ariadne. About Grace. Thomas had wondered how Alastair felt about both of them, and Charles’ engagement to both. Clearly he didn’t take them very well. 

Alastair recovered quickly.

"You're not gonna be useful if you're stressed and nervous," Alastair said, combing a hand through his blonde hair. Thomas admitted to himself that he missed Alastair’s stark black hair. 

An idea was conjuring itself behind Alastair's dark eyes. It seemed to Thomas that he was actually debating if he should go through with it. With a sigh of resignation he made his way over to Thomas. He grabbed Thomas lightly by the front of his waistcoat. 

"I’m sure you can guess about Charles and I. How we're-how we're more than just close friends," Alastair said, abruptly. He seemed scared to say it, even in this small room with just the two of them.

"Yes," Thomas whispered. He didn't think he was making himself that obvious about how Alastair made him feel. But Thomas supposed he was like an open book. Of course Alastair had noticed Thomas's clipped tone when he spoke to Charles after Alastair had arrived. Thomas knew Alastair loved Charles, and it hurt Thomas not being able to tell if Charles returned the same feelings. "I don't mind any." Thomas added quickly, though he most definitely did. Just not for the reason most people would mind. 

"That's not why I'm saying this," Alastair huffed. "I like...men, Thomas. I wanted to make sure you feel the same to...to some degree, I suppose." 

"I...yes," Thomas whispered again. Admitting to it aloud was so much different than in your head. And Thomas couldn't believe the first person he told was  _ Alastair Carstairs _ . "Yes, I do like men."

"Good," Alastair said quickly. "So you'll have no qualms about myself sucking you off."

" _ What? _ " Thomas flinched back with shock, nearly knocking over the glass that held the last of the malos root. 

"Bloody hell don't ruin everything we worked for you giant!" Alastair said, alarm in his voice. Thomas carefully put the root on the other side of the table. "I'm just saying it'll help you release some tension, maybe then you won't be so goddamn jumpy."

"But, Charles-"

"Charles doesn't care what I do," Alastair said. A crooked smile spread across Alastair's face. "He gets to have two fiances, I get to have a Lightwood in my mouth. That seems fair."

Thomas wasn't entirely sure if it was.

"Unless you don't want me to," Alastair said. "I'm not going to take anything you don't want to have taken." 

If Thomas was nervous before, anxiety pulsed through him just as the blood from his fast heart did. He did want it, badly in fact. What had he told Anna in her apartment? That he only wanted one name in his book of conquests. But he didn't think the circumstance would arise like this. He didn't think Alastair of all people would be  _ offering  _ it to him. 

Without a word, Thomas nodded. He was worried his voice would betray too much of what he was feeling. 

Alastair patted Thomas on the shoulder before dropping to his knees. "You needn't have to worry Thomas," Alastair said. "According to Charles I'm very good at this act."

Thomas didn't have very long to register that sentence as Alastair started unbuckling Thomas's trousers. Thomas sputtered "W-wait. What about you? I'm not skilled enough to offer anything like this in exchange-"

"It's fine," Alastair said, pulling down Thomas's pants and freeing Thomas's cock. "I'm used to only giving."

Thomas wanted to feel anger at Charles, but as soon as Alastair's hands were on him all other thoughts left his mind. 

"Good to know that your height isn't the only thing that's big," Alastair said. Thomas felt a blush spread across his face.

He wasn't hard, he hadn't been prepared for antidote making to turn out this way, but as Alastair pumped him he felt waves of desire wash over him. This is what he wanted wasn't it? His body most assuredly did, each touch made by Alastair felt like fire on his skin. But as Alastair worked Thomas's dick, Thomas himself felt a yearning for a different kind of love. 

When Thomas was fully hard, Alastair took him in his mouth. Thomas sucked in breath between his teeth. Pushing away the uncomfortable thought of Alastair sucking off Charles, Thimas reveled in how experienced Alastair was at this. The feeling of Alastair's wet mouth and tongue around his cock sent bolts of pleasure through him. He covered his mouth to stifle his moans.

Alastair took Thomas out of his mouth for a second. He was breathing hard. "You're not even going to give me the satisfaction of hearing your voice?" 

Thomas felt his face heat up again. He felt like a schoolgirl blushing at whatever a hot boy had said. He took his hand away from his mouth. He made sure to moan just a little louder for Alastair. 

Alastair was focusing mostly on the tip—he hadn't been joking about Thomas's length—using his hand to stroke the part of the shaft he couldn't take. 

Thomas put a hand in Alastair's hair, combing through it gently. Maybe Thomas wanted for at least a moment to imagine that they weren't in the situation they were in. Maybe he wanted to believe that this was something romantic between the two of them. 

Alastair just took the loving gesture as encouragment and went to take more of Thomas's cock in his mouth. 

Thomas moaned again, and subconsciously, his grip on Alastair's hair tightened. Thomas leaned against the table, happy that they had moved the ingredients elsewhere. He closed his eyes, letting the feeling of Alastair sucking and stroking his cock wash over him. 

"Ah-shit-please." Thomas gasped. He heard Alastair make a deep noise in his throat.

As Alastair picked up his pace, bobbing his head up and down on Thomas's cock, he put his other hand in Alastair's hair. He bit his lower lip. He wanted this to keep going, but at this rate he wasn't sure how much longer he was going to last. 

Thomas reached his peak when Alastair moved and took his whole length. The flash of total pleasure had caught Thomas by surprise, and he felt himself cum down Alastair's throat. He was only brought out of his ecstasy by Alastair's gags.

"Ah! Ah! Sorry!" Thomas let go of Alastair's hair as he started to sputter and cough. Thomas wasn't quite sure what to do so he went to redoing his trousers. Awkwardly

"Christ, a little warning would've been nice!" Alastair rasped out.

" I hadn't been expecting it either!" 

"Whatever." Alastair brushed a hand through his hair, trying to fix where Thomas had ruffled it. "No mess to clean up. Is that antidote done yet?"

Thomas had for a second forgotten everything else and then the antidote came back to him.

"Uh, yes. Yes I think so," Thomas said.

"Good, I wanna get out of here and look for my sister as soon as possible."

The next few moments were very quick, Alastair acting as if nothing had even occurred. Thomas felt a slight pain in his heart that they couldn't even talk about it, before Alastair was rushing him out the door, the completed antidote in hand, calling a handsome to take them to the institute. 

At least they were on decent speaking terms now, Thomas thought. There'll be time later to talk about everything.


End file.
